Picket fences have traditionally been made from wood. Whilst wood enables a relatively simply construction to be provided, it has various disadvantageous. Wood is subject to rot. Consequently, after erection of the fence. it has to be painted and then repainted at regular intervals, to keep the fence in good condition. Also, assembly of a wooden fence is time consuming. Usually, the individual picket and horizontal rails have to be cut to length, and then assembled. If a uniform and neat appearence is to be provided, care has to be taken when cutting the pickets and rails. The fence is then assembled using nails or screws, which is relatively time consuming. Such a construction also cannot readily be disassembled, and then reassembled at an alternative location.
Various proposals have been made for forming picket fences and the like from other materials, notably steel and U.K. Pat. No. 29,939 of 1897 (Miller), U.S. Pat. Nos. 30,507 (Stratton), 966,969 (Webb), 2,766,967 (Roberts), 2,919,112 (Cofield), 3,095,184 (Boxberger), 3,212,754 (Revell et al), 3,411,752 (Bos) and applicant's U.S. Pat. No. 4,625,948 disclose fence or like constructions.
The Miller U.K. Pat. No. 29,939 discloses fencing which is capable of accomodating itself to the inclination of the ground on which it is erected and incorporates upper and lower longitudinal, channel section bars which receive a plurality of equidistantly arranged vertical bars of angle iron. The vertical bars are received in the upper and lower longitudinal bars in holes of shapes corresponding to that of the vertical bars and of a size sufficient for the vertical bars to fit loosely therein. The vertical bars are retained in the longitudinal bars by means of tongues produced by piercing the vertical bars. The tongues are located such that they project respectively over the lower longitudinal bar and under the upper longintudinal bar.
The Stratton U.S. Pat. No. 30,507 discloses a picket fence in which vertical pickets are mounted on upper and lower transverse rails by means of pairs of hooks provided on the pickets and adapted for fitting into corresponding notches of the rails. As with the Miller patent discussed above, it is claimed that the disclosed fence contruction admits of the raising or lowering of the ends of the transverse rail to suit varieties of grade.
The Webb U.S. Pat. No. 966,969 relates to a line and corner fence post and bracer that incorporates posts with horizontal braces extending therebetween. Each post includes a plurality of upstruck tongues or clips arranged in pairs and normally utilized for retaining line wires in position, but also for anchoring a longitudinal brace strip. In the main embodiment, however, the brace strips are located in openings formed in flanges of the posts.
The Roberts U.S. Pat. No. 2,766,967 discloses a knock down fence construction, that incorporates horizontal metal straps with tabs punched therein. It also has vertical slats, with notches cut in the edges. These notches correspond to the punch tabs, and the slats are bowed, to enable them to engage the tabs. The construction is intended as a light weight low fence for the edge of flowerbeds and the like.
The Cofield U.S. Pat. No. 2,919,112 discloses a collapsable fence arrangement. For this purpose, horizontal stringers and vertical pickets are rivetted together, to enable relative rotation therebetween.
The Boxberger U.S. Pat. No. 3,095,184 discloses a fence construction to be fabricated almost entirely of sheet metal. Two extruded stringers of stepped channel shape are mounted to extend in horizontal directions and are vertically spaced apart. The stringers include elongated slots for receiving the hook shaped end portions of vertical slats of heavy gauge sheet metal.
The Revell U.S. Pat. No. 3,212,754 discloses an interlocking fence structure. A top rail has specially formed s1ots and tongues, for engaging vertical pickets. The pickets similarly have a complex cross-section and three projections for securing them in the top rail.
The Bos U.S. Pat. No. 3,411,752 discloses a guardrail construction, such as a balcony balustrade. Here, generally I-section vertical members are provided. These members are accomodated in corresponding openings of top and bottom horizontal rails. Pins secure the vertical members in the horizontal rails. To cover the tops of the vertical members protruding through the top horizontal rail a sheet form handrail is provided.
Applicant's U.S. Pat. No. 4,625,948 discloses a picket fence construction having transverse rails and a plurality of pickets adaped to be mounted in the rails. The pickets are hung by means of a tongue and engaging link arrangement. The rail includes a tongue for each picket, and each picket includes an engaging link, or alternatively the tongues and links are reversed.